The Shibatas head for Rogetsu, an island just off the coast, which has the cliff shaped like a monkey's face. Tsugumi informs that she saw the island in a vision and believes they'll find another of Ai's clients. They meet a young man with a bandged arm and he tells them the history of Rogetsu. At a family-owned hotel, a young woman named Mina Minato ignores her Aunt Fujie's shouting and runs off. In a flash back, Mina discovered her aunt in the shower, with a deep cut on her hand, and she thinks her aunt has gone insane. Then, Ai, Hone, and Ren follow her around, and it is revealed that Mina received the black straw doll. The boat comes ashore and Mina is delighted to see her boyfriend, Yuji Numata has come home from the hospital. Mina then spots her aunt, who had followed her to the dock, and she leaves. Tsugumi then points out that Mina is the new client of Hell Girl. They go around to ask people of Mina, but the locals turn them away, as they are not comfortable with outsiders.

Finally, they catch a break; the local restaurant owner tells the Shibatas about the Minato Inn and of the owner, Fujie, and her niece, Mina. He then tells the story of Mina's mother, Satsuki; she fell in love with a man, but he left her when Mina was born, and Satsuki returned to Rogetsu and stayed with her sister, Fujie. Then, some time later, one of Satsuki's shoes were found on the beach, but her body was never found, although the locals believed she committed suicide. Suddenly, the owner panics as Ren's eye appears on Hajime's chest and he orders them to leave. At the inn, Fujie is in the shed, talking to someone, but the audience never sees the person. At the island's junior high school, the principal welcomes the Shibatas and they ask questions about Mina and Fujie. The principal explains that both Fujie and Mina were very close when she was young, but during the middle of Mina's high school year, she quit, probably because she would take over the inn. He then mentions that a boy, Yuji would call her over the phone, but Fujie couldn't accept it for some reason. Yuji is employed by the department of marine studies and the two would get together, but Fujie would forbid Mina because he isn't a local and Mina decided to rebel against her aunt.

At the cliffs, Yuji tells Mina that he was attacked by a diver while underwater, and Mina believes it was her aunt. She explains that her aunt came home and Mina saw her in the shower with a deep cut, this would explain Yuji's defense against the mysterious diver. At the school, Tsugumi tells Hajime that it was Mina that used one of the computers to summon Hell Girl to take her aunt to hell.

The Shibatas check at the inn to spend the night, but they find Fujie as a fine woman. She informs that Mina had left that afternoon and they will have to wait for her. When Fujie leaves, Tsugumi has a vision of cherry blossom trees in bloom and Ai specks through her and asks if they will leave. Hajime realizes that Mina is nearby and he goes after her. At the cliffs, Yuji is about to throw the straw doll that Mina had shown him, but she wants to use it to send her aunt away to hell. At that moment, Hajime arrives and urges them not to pull the string. After explaining the consequences, Mina and Yuji decide to leave the island, and return to see if Fujie would understand their feelings, but Hajime doesn't like it. The two run back to the inn to take what they need, but Mina hears her aunt talking to someone in the shed, and thinks that she hears her mother's voice. Mina then goes to investigate, much to her sentimental confusion. To her horror, Fujie has been talking to the dismembered skeleton of Satsuki, who was kept in the cellar of the shed for fifteen years. In a flashback, it is revealed that Fujie murdered her own sister with an axe because Satsuki hated the island and wanted to return to the mainland with Mina, and the idea of being separated and left alone drove her insane.. Then, Fujie takes the ax and attacks Mina, and even cuts her hand, when Mina revealed the black straw doll. Fujie is about strike when Yuji runs into the shed/cellar and stops her, but she kicks him away. She raises the ax and is about to strike them both, when Mina grabs the doll and pulls the string, just in time, much to Hajime and Tsugumi's dismay as they arrive. On Ai's ferryboat, Fujie cuddles the skull of Satsuki, informing they will always be together.

The Shibata's return to the main land, having failed, again to stop Hell Girl. Although Tsugumi states it would've end tragically for Mina and Yuji and Hajime agrees. Mina and Yuji watch the boat leave and Mina reveals the black fire symbol on her chest.